Software RAID 5 - a long story - Hardware

This is a discussion on Software RAID 5 - a long story - Hardware ; Hello --
I'll try to keep this as brief as I can.
A while back I created an LVM array from 4 1TB Maxtor externals. This LVM
was to serve as a temporary data dump, while two of my internal ...

Software RAID 5 - a long story

A while back I created an LVM array from 4 1TB Maxtor externals. This LVM
was to serve as a temporary data dump, while two of my internal HDs, were
RMA'd.

During the waiting period, one of the Maxtors failed, and I lost my data.
Having learned my lesson, I pulled the Maxtor for RMA, and resconstructed
the three remaining as a RAID5 array, then created an LVM volume with it.
Lovely.

When the failed Maxtor's replacement returned, I decided to grow the RAID5
array with it. Everything was going fine until one of the other Maxtors
decided to die on me as well. Needless to say I was unimpressed.

The newly-failed unit has been pulled and RMA'd , but I notice that whenever
the just-replaced unit falls asleep, it "falls off" the SCSI chain and
disappears.

Usually, I reboot and then re-assemble the array (this is only temporary
after all), but this time I decided to re-add the device after switching it
off then back on again. Its designation changed from /dev/sdn1
to /dev/sdq1. However, mdadm added it as a spare device, instead of
a "normal" raid component, and of course updated its superblock
accordingly.

"Total Devices" should be 3 not 4, since no spares were specified at
creation time. The drive contents have not been modified, so what I need to
do is change the major/minor number of the drive in the MD superblock. Is
this possible? The "real" major and minor numbers are:
/dev/sdn(8,208) /dev/sdn1(8,209)